Screwdriver with substitutable bit

ABSTRACT

This screwdriver comprises a sleeve shank which at its end portion is provided with a slot and a center cavity bisecting said slot into which a bit is substitutionally inserted. The sleeve shank end is covered with a sleeve adapter of plastic material which serves to hold and suspend the screw.

United States Patent Inventor Kats'uyuki Totsu No. 4-7, S-ehome,oshiage, Sumida-ku, Tokyo, Japan Appl. No. 737,871 Filed June 18, 1968Patented Oct. 12, 1971 Priority June 24, 1967, Mar. 6, 1968 Japan42/40239 and 43/ 14040 SCREWDRIVER WITH SUBSTITUTABLE BIT 9 Claims, 22Drawing Figs.

U.S. Cl 279/102 Int. Cl B25g 3/10, B25b 15/00 Field of Search 145/50;30/340, 329, 336, 342; 287/126; 279/102, 93, 104, 96

References Cited UNITED STATES PATENTS 10/1966 Scott et a1. 30/3425/1899 Sawyer 145/50-1 1/1907 North 145/50-1 8/1919 Mowers 145/50-1 UX6/1933 Beaver 279/93 2/1942 Snyder 279/93 X FOREIGN PATENTS 1/1914 GreatBritain 145/50-1 Primary Examiner-Robert C. Riordon AssistantExaminer-Roscoe V. Parker, Jr. Attarney-Jecies and Grenside ABSTRACT:This screwdriver comprises a sleeve shank which at its end portion isprovided with a slot and a center cavity bisecting said slot into whicha bit is substitutionally inserted. The sleeve shank end is covered witha sleeve adapter of plastic material which serves to hold and suspendthe screw.

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FIGZZ INVENT OR SCREWDRIVER WITII SUBSTITUTABLE BIT BACKGROUND OF THEINVENTION FIGS. ll(a) (b) to 14(a) (b) show front elevations and lateralviews in section of the alternative embodiments of the 7 bits;

This invention relates to improvements in the screwdriver,

and more particularly to the screwdriver of the type employing asubstitutable bit.

In the screwdriver heretofore used, the tendency of abrasion anddetriment usually occur at the bit portion of the screwdriver due tocontinuous driving and disengaging operations and as a result thescrewdriver in its entirety is not serviceable for further use since thebit is integrally constructed with the shank of the screwdriver. In thatcase the screwdriver should be discarded, otherwise the bit will beground or polished for restoration under the special care.

SUMMARY OF THE INVENTION Generally, therefore, it is an object of thepresent invention to obviate the above and other disadvantages anddifficulties and to provide a novel screwdriver which has certainstructural and functional features of advantages over the similarscrewdriver of the prior art and is economic in manufacture and simplein construction.

A principal object of the invention is to provide a screwdriver having asleeve shank provided at its extremity with a slot and a center cavitybisecting the said slot serving to receive the bit.

Another object of the invention is to provide a bit which comprises ablade portion and a tail piece and is substitutionally inserted in theslot and the center cavity provided at the end of the sleeve shank ofthe screwdriver.

A further object of the invention is to provide a bit having a pinadapted to be rigidly engaged with a screw slot provided in the screwhead thereby holding the screw to carry the same to the position wherethe driving operation is effected.

Still another object of the invention is to provide a new screwdriver inwhich a sleeve shank end containing the bit is covered with a sleeve ofplastic material which at its open end envelopes the screw head therebyholding the screw to carry the same to the position where the drivingoperation is effected.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

In brief the screwdriver embodying the invention comprises the sleeveshank provided at its extremity with the slot and the openended cavitybisecting the said slot into which the substitutable bit is rigidlyinserted. The open-ended cavity is positioned in the center of thebottom plane of the sleeve shank and of the greater depth than that ofthe slot. The sleeve shank at its extremity is further provided withmeans for holding and suspending the screw internally or externally.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of thenature and object of the invention a reference should be had to thefollowing detailed description taken in connection with the accompanyingdrawing, in which the same reference numerals designate the same orsimilar parts throughout the drawings;

FIG. I is a fragmentarily enlarged lateral view of the end of the sleeveshank free of the bit;

FIG. 2 is a bottom view of FIG. 1;

FIG. 3 is a longitudinally sectioned lateral view of FIG. 1;

FIG. 4 is a front elevation of the bit according to the invention;

FIG. 5 is a lateral view of FIG. 4; I

FIG. 6 is a fragrnentarily enlarged front view of the end of the sleeveshank associated vention;

FIG. 7 is a sectional view of FIG. 6;

FIG. 8 is a longitudinally sectioned lateral view of FIG. 6;

FIG. 9 is a front elevation of the bit embodying the inven-' tion wherea protuberance is provided at the middle of the lower edge;

FIG. 10 is a perspective view of the screw having the screw slot withthe center cavity bisecting the same;

with the bit according to the in- FIG. 15 is a longitudinally sectionedview of the sleeve shank end having a slot provided with a bypath and avertical channel; 7

FIG. 16 is a bottom view of FIG. I5;

FIGS. 17(a) (b) and 18(a) (b) are back and lateral views of the bitsimilar to FIGS. 9 and 14 but provided with pins adapted to engage withthe screw slot thereby holding the screw;

FIG. 19 depicts the state that the bit with the pin as illustrated inFIG. 18 is inserted in the slot with bypath and vertical channelprovided in the sleeve shank end;

FIG. 20 is longitudinally sectioned view showing the state that the bitwith the pin fitted to the shank as illustrated in FIG. 19 is insertedin the screw slot of the screw head thereby holding the screw;

FIG. 21 is a longitudinally sectioned lateral view in fragmental of theshank end with the bit as illustrated in FIGS. 4 and 5 holding the screwthrough an outer sleeve adapter;

FIG. 22 is a longitudinally sectioned lateral view in fragmental similarto FIG. 20 showing that the outer periphery of the sleeve shank end isthreaded.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated by way ofexample in the drawings, the characteristic feature of the inventioncomprises a sleeve shank which at its one end is provided with a slotand the center cavity bisecting the said slot which is positioned in thecenter of the shank end and about the longitudinal axis of the sleeveshank, and a bit which is substitutionally and rigidly inserted in theslot and the center cavity.

In FIGS. [to 3, the shank end I is provided with a slot 2 and the centercavity 3 which bisects the said slot 2 and is positioned in the centerof the shank end and about the longitudinal axis thereof. Alternatively,the shank end may be provided with the slot with a bypath and/or avertical channel serving to receive a specially designed bit ashereafter described.

It will be noted that the center cavity 3 has a greater diameter thanthe width of the slot 2 and a greater depth than that of the said slot2.

In FIGS. 4 to 8, the bit 4 according to the invention comprises a blade5 and tailpiece 6 and is formed preferably of elastic steel although thenature of the material for forming the bit may optionally be selected asdesired according to the purpose. The bit 4 is of substantially the samedimensions as the slot 2 in its horizontal length but greater than theslot 2 in its vertical length, so that the blade when the bit isinserted in the slot 2 protrudes over the slot 2 for engagement with thescrew slot of the screw head. Moreover, it will be noted that thethickness of the bit 4 is substantially the same as width of the slot 2,so that the bit 4 is tightly engaged with the slot 2. The tailpiece 6 issomewhat bent to one side at its root 7 as shown in FIG. 5, so that thetip of the tail 6 when forced into the center cavity 3 engages rigidlywith the inner wall thereof due to the elasticity of the bent tailpieceas will be apparent from FIG. 8. For this reason, the center cavity 3may be of any desired shape although the cylindrical shape is ratherconvenient in the mechanical working.

On the insertion of the bit 4 in the slot 2, the tailpiece 6 is firstguided into the center cavity 3 and then the edge of the blade portion 5is tapped with a certain tool until the upper end of the blade portionfaces with the bottom surface of the slot 2. Further, since thetailpiece 6 is somewhat bent as shown in FIG. 5, the top end thereof ispressed to the inner wall of the center cavity and does not disengagespontaneously during the screwing or unscrewing operations unless thebit is forcefully withdrawn.

The bit when it is to be replaced by a fresh one may readily bewithdrawn with a tool such as pincers.

In FIG. 9, the blade edge 5 at its middle is provided with a smallprojection 8, which is particularly applicable to the screw of the typeemploying the slot possessing a center cavity of a greater depth thanthat of the screw slot as shown in FIG. 10. It will be appreciated thatthe projection 8 when inserted in the cavity 9 provided in the screwhead 10 serves as the further means to prevent the driver blade fromslipping sideways out of the screw slot 11.

FIGS. 11(0) (11) to 14(a) (b) show other embodiments of the bits havingno tailpiece in which a bit 12 shown in FIG. 11 comprises a steel pieceof substantially rectangular shape and its center portion is opened toform a protuberance 13 having the same ability as the tailpiece 6.According to this embodiment, the opposite edges 14 and 15 are of thesame thickness so that if one edge is worn-out or damaged then the otheredge may be used for the further driving purposes.

In FIG. 12, the edge 15 is of less thickness than that of the edge 14 sothat the bit may be applicable to screw slots of different widths.

In FIG. 13, a curved pin 16 in its one end is welded to the end of thebit 4. According to this embodiment, only the edge 14 is serviceable asa blade to be engaged with the screw slot. The pin 16 may be formed ofanelastic steel while a blade may be selectively formed of a hard metalas desired according to the purpose.

In FIG. 14, a part of the bit 12 below the protuberance 13 is cut away,so that the edge 14 is divided into two symmetrical blade pieces 17.This type of the bit is rather convenient in the manufacture. It will beappreciated that such the divided blades 17 have the same effect as thestraight and continuous edge 14 since the driving force generally exertson the opposite outer ends of the edge.

On application of the bits as shown in FIGS. 11 to 14 which have notailpiece, the slot 2 may be provided with a bypath 18 serving toreceive the protuberance 13 or the curved pin 16 of the bit 12 as shownin FIGS. 15 and 16 thereby ensuring smooth insertion of the bit into theslot and precluding an undesireable displacement of the bit during thedriving or disengaging operation.

In FIGS. 17 and 18, the bits at their respective rear sides are providedwith 18, the 20 and 21 of elastic material serving to hold the screw. Itwill be noted that one end of the pin is welded to the end of the tailor bit while the other end of the pin being opened outwardly. When thebit associated with the pin is inserted in the slot, the pin is pressedtoward the bit resisting to its outward elasticity as shown in FIG. 19.In this state, the pin pressed toward the bit keeps stronger elasticpotency than the original state, i.e. before the pin being inserted inthe slot of the driver shank. As is shown in the drawing, the bit andthe pin are kept in very close but forming a clearance therebetween andready for insertion in the screw slot. Accordingly, when the bit isinserted in the screw slot, the pin is further pressed by the inner wallof the screw'slot or by the center cavity provided in the screw head andas a result the screw 22 is rigidly held as shown in FIG. 20. In case ofthe bit of the type as illustrated in FIG. 18 which has no tailpiece theshank end I may be modified to the type as illustrated in FIG. 16wherein a vertical channel 19 serving to receive the pin 20 is providedon the opposite side to the bypath 18.

In FIGS. 21 and 22, the outer periphery of the shank end 1 is coveredwith a sleeve adapter 23. This sleeve adapter 23 is formed of softplastic material for example such as vinyl chloride and when it isapplied around the shank end, the diameter at the lower opening of thesleeve adapter tends to become smaller than that of the shank end, sothat the outer periphery of the screw head is held by the inner wall ofthe sleeve end 24 as shown in FIG. 21. On the other hand, the upper endof the sleeve adapter 23 falls in the recess 25 provided around theupper portion of the shank end 1, so that a step 26 of the recess 25precludes the sleeve adapter 23 from sliding upwardly along the outerperiphery of the sleeve shank.

It will thus be seen that the screwdriver in accordance with theinvention provides a substitutable bit and a prositi e holding ofthescrew therebyf acilitatihg m's'crwm'g or unscTEwing operationconveniently. Further according to the invention, the bit has an uniformthickness through all its area and is not tapered as can be seen in theordinary blade of the screwdriver. Accordingly, when the bit is engagedwith the screw slot, both sides of the bit are tightly faced with theinner sidewalls of the screw slot and therefore the driving operationmay be carried out more effectively with less fear that the bit willjump out of the screw slot.

Moreover, since the structure is relatively simple, the screwdriver inaccordance with the invention may be manufactured at a low cost and alsothe bit only may be manufactured with negligible cost. Further, it willbe appreciated that it is an important merit of the invention that thebit only which is considered as the most vital part of the driver may beformed of a hard steel of selected quality while the shank may be formedof ordinary metal at reduced cost.

While certain preferred embodiments of the invention have beenillustrated by way of example in the drawings and particularlydescribed, it will be understood that modifications may be made in theconstructions and that the invention is no way limited to theembodiments shown. For example, while the invention has been describedas relating the screws of rounded heads, it would not differ from thepresent invention to make use of it in connection with flat screw.

What is claimed is:

1. In combination, a screwdriver shank having an axially extendingcavity and a diametrically extending slot in the operative end of saidshank, said cavity communicating at the lower end thereof with saidslot, and a bit comprising a blade member and a cooperating resilientmember angularly oriented with respect to the blade member, said bitbeing detachably positioned within the cavity with its blade membertightly engaged within said slot and with a part only of said resilientmember in rigid engagement with a portion only of the interior walldefining the cavity and forming thereby the sole retaining means forretaining said bit within said cavity, one end of said blade memberprotruding beyond said slot for engagement with a screwhead.

2. The combination according to claim 1, wherein said resilient memberis resiliently urged substantially in the plane of the remaining portionof said blade member by contact with the wall of said cavity uponinsertion of said blade member in the slot of said shank, said bitbetween the regions of contact with the wall of the cavity and said slotbeing spaced from the cavity wall.

3. The combination of claim 1, wherein the end of said blade memberprotruding beyond said slot is provided with a projection adapted toseat in a slot ofa screwhead.

4. The combination according to claim 2, wherein said resilient memberis provided with resilient pin angularly oriented with respect to themember.

5. The combination of claim 1, wherein the diameter and depth of saidcavity are greater than the thickness and depth respectively of saidslot.

6. The combination according to claim 5; wherein the apertured end ofsaid shank is provided with a sleeve adapter the upper end of whichcontacts a shoulder formed on the outer periphery of said shank and thelower end of which is adapted to embrace a screwhead.

7. The combination according to claim I, wherein said resilient memberis an angular tang welded to the end of the blade member remote fromsaid one end.

8. The combination according to claim 1, wherein said one end of theblade member is provided with a pair of bifurcations serving as bladepieces, said resilient member comprising a tang separating saidbifurcations, said tang projecting from one face of the blade member, aresilient pin being provided on the other face of said member and beingangularly oriented with respect thereto, said pin being substantiallythe same length as the blade member.

9. The combination according to claim 8, wherein said cavity includes anaxially extending bypath groove formed in one wall defining saidslotizmtl includes a channel formed in the other wall defining saidslot, said channel being adapted to receive said pin and said groovebeing adapted to receive said tang.

1. In combination, a screwdriver shank having an axially extendingcavity and a diametrically extending slot in the operative end of saidshank, said cavity communicating at the lower end thereof with saidslot, and a bit comprising a blade member and a cooperating resilientmember angularly oriented with respect to the blade member, said bitbeing detachably positioned within the cavity with its blade membertightly engaged within said slot and with a part only of said resilientmember in rigid engagement with a portion only of the interior walldefining the cavity and forming thereby the sole retaining means forretaining said bit within said cavity, one end of said blade memberprotruding beyond said slot for engagement with a screwhead.
 2. Thecombination according to claim 1, wherein said resilient member isresiliently urged substantially in the plane of the remaining portion ofsaid blade member by contact with the wall of said cavity upon insertionof said blade member in the slot of said shank, said bit between theregions of contact with the wall of the cavity and said slot beingspaced from the cavity wall.
 3. The combination of claim 1, wherein theend of said blade member protruding beyond said slot is provided with aprojection adapted to seat in a slot of a screwhead.
 4. The combinationaccording to claim 2, wherein said resilient member is provided withresilient pin angularly oriented with respect To the member.
 5. Thecombination of claim 1, wherein the diameter and depth of said cavityare greater than the thickness and depth respectively of said slot. 6.The combination according to claim 5; wherein the apertured end of saidshank is provided with a sleeve adapter the upper end of which contactsa shoulder formed on the outer periphery of said shank and the lower endof which is adapted to embrace a screwhead.
 7. The combination accordingto claim 1, wherein said resilient member is an angular tang welded tothe end of the blade member remote from said one end.
 8. The combinationaccording to claim 1, wherein said one end of the blade member isprovided with a pair of bifurcations serving as blade pieces, saidresilient member comprising a tang separating said bifurcations, saidtang projecting from one face of the blade member, a resilient pin beingprovided on the other face of said member and being angularly orientedwith respect thereto, said pin being substantially the same length asthe blade member.
 9. The combination according to claim 8, wherein saidcavity includes an axially extending bypath groove formed in one walldefining said slot and includes a channel formed in the other walldefining said slot, said channel being adapted to receive said pin andsaid groove being adapted to receive said tang.